Scotland Yard detectives attempt to solve a spate of safe robberies across England beginning with clues found at the latest burglary in London. The film is notable for using a police procedural style made popular by Ealing in their 1950 film The Blue Lamp. It is known in the US as The Third Key.
Jack Hawkins
as Supt Tom Halliday
John Stratton
as Sergeant Ward
Dorothy Alison
as Mary Halliday
Michael Brooke
as Tony Halliday
Sam Kydd
as Police Constable in Information Room
Glyn Houston
as Detective Sergeant in 'Q' car
Richard Leech
as Nightwatchman / Gilson
Newton Blick
as Deputy Commander
Geoffrey Keen
as Chief Superintendent Jim Malcolm
Sydney Tafler
as Stone
Peter Burton
as Creasey
George Rose
as Slob
